Appendix A: Some Technical Details of Various
Apple II The computer used a MOS 6502 microprocessor
operating at 1 MHz with 8K bytes of ROM and 4K bytes of
dynamic RAM, expandable to 48K. The integral video
system could display 24 rows of 40 characters in upper
case only. Each character was a 5 by 7 dot matrix. The
display also had a graphics mode with high and low
resolutions. In low resolution the 40 horizontal by 48
vertical locations could be in one of 15 colors. In high
resolution the screen could display a maximum of 280
horizontal by 192 vertical positions in 4 colors. The
video system also included a mixed mode in both low and
high resolutions, with graphics and four lines of text
at the bottom of the screen.
Apple lie The computer used a 65C02 microprocessor
operating at 1.023 MHz with 16K bytes of ROM and 128K
bytes of RAM. The unit had one 5.25-inch 140K byte Alps
floppy disk drive. The monitor could display 2 4 lines of
40 or 80-column text. The video system also had three
graphic modes. The low-resolution mode had 40 horizontal
by 48 vertical pixels in 16 colors. The high-resolution
mode had 280 horizontal by 192 vertical pixels in 6
colors. Then a double-high-resolution mode had 560
horizontal by 192 vertical pixels in 16 colors. The
single 5.25-inch Alps half-height floppy disk drive was
built-in. The disk controller was the IWM (Integrated
Woz Machine) chip as used on the Macintosh computer. The
disks were single-sided with 35-tracks and 16-sectors.
Apple lie The computer used a MOS 6502A
microprocessor operating at 1 MHz with 16K bytes of ROM
and 64K bytes of RAM, expandable to 128K. The storage
system supported six 140K byte 5.25-inch floppy disk
drives. The terminal could display 24 lines of 40-column
text in both uppercase and lowercase characters. Each
character was a 5 by 7 dot matrix. The computer had two
standard graphic modes. A low-resolution mode produced
40 horizontal by 48 vertical pixels with 16 colors. The
AA/2 A History of the Personal Computer
standard high-resolution mode produced 280 horizontal by
192 vertical pixels with 6 colors. The video system
retained the Apple II mixed mode in both low and high
resolutions, with graphics and four lines of text at the
bottom of the screen. Seven slots were available for
peripheral boards. The unit included an additional 60-
pin auxiliary slot on the motherboard that provided for
one of two optional cards.
The two optional cards could either display 80
columns of text or both 80 columns of text display and
an extension of memory to 12 8K bytes. The extended
memory 8 0-column option card and suitable software
enabled double-density graphics in both low and high-
resolution modes .
Apple IIGS The computer used a Western Design Center
W65C816 microprocessor operating at 2.8 MHz with 128K
bytes of ROM and 256K bytes of RAM, expandable to 8
megabytes. The microprocessor had a 24-bit address bus
and an 8-bit data bus. The unit had two operating modes:
a native mode of 2.8 MHz and an Apple lie emulation mode
of 1.02 MHz. The storage system included support for
both 3.5-inch 800K byte and 5.25-inch 140K byte floppy
disk drives. The terminal could display: 24 lines of 40
or 8 0-column text. Graphic modes varied from low-
resolution with 40 horizontal by 48 vertical pixels in
16 colors, to super-high-resolution with 640 horizontal
by 200 vertical pixels in 4 colors. An Ensonig digital
synthesizer chip with 64K bytes of dedicated RAM
provided new sound capabilities. The unit had a 44-pin
memory expansion slot and seven 50-pin slots for
Apple III The computer used a Synertek 6502A
microprocessor operating at 2 MHz with 96K bytes of
memory, expandable to 12 8K. The unit included one built-
in 5.25-inch, 143K byte floppy-disk drive. The terminal
could display 24 lines of 80-column text. Graphic modes
were 560 horizontal by 192 vertical pixels in monochrome
and 280 horizontal by 192 vertical pixels in 16 colors
or 16 shades of gray. The computer had four slots for
peripheral cards that had certain compatibility with
Apple II cards. An aluminum chassis acted as a radio
freguency shield and as a heat sink that eliminated the
Appendix A AA/3
need for a cooling fan. Three additional disk drives
could be daisy-chained from a rear connector. The Apple
III floppy-disks had a new 16-sector format (compared
with a 13-sector format on the Apple II) .
Lisa The computer used a Motorola MC68000
microprocessor operating at 5 MHz with 1 megabyte of
RAM. The storage system had two Twiggy 5.25-inch 860K
byte floppy disk drives and a separate 5 megabyte
Winchester-type hard disk named ProFile. The display was
a 12-inch monochrome monitor with a resolution of 720 by
364 pixels. The computer used four additional
microprocessors. Two from National Semiconductor
controlled the keyboard and mouse, a 6504 controlled the
two floppy disk drives and the hard disk controller had
a Z-8. The floppy disk drives maintained a constant data
density between the outer and inner tracks.
Macintosh The computer used a Motorola MC68000
microprocessor operating at 7.83 MHz with 64K bytes of
ROM and 128K bytes of RAM. The storage system had one
integral 3.5-inch 400K byte floppy disk drive from Sony.
The 3.5-inch disks were single-sided with 80 tracks. The
storage system recorded data at a constant rate similar
to the Lisa Twiggy drive. A connector provided for an
optional second external 3.5-inch floppy disk drive. The
display was a 9-inch monochrome monitor with a
resolution of 512 horizontal by 342 vertical sguare
pixels. There were no expansion slots, but two high-
speed serial ports provided for connection of
peripherals. The separate keyboard had 58 keys (59 in
the international version) , but no function or cursor
Macintosh II The computer used a Motorola MC68020
microprocessor operating at 16 MHz with a floating-point
coprocessor and one megabyte of RAM, expandable to 8 MB.
The unit had an open NuBus architecture developed at MIT
with six slots for plug- in boards. The 13-inch color or
12-inch monochrome monitor could display 640 by 400
pixels as compared to the 512 by 342 pixel display on
the previous Macintosh computers. The display system
could have either 16 or 256 colors or shades of gray.
AA/4 A History of the Personal Computer
Macintosh Portable The computer used a Motorola
CMOS 68000 microprocessor operating at 16 MHz with 1
megabyte of RAM expandable to 2 megabytes. The unit
included a built-in 3.5-inch 1.4 megabyte floppy-disk
drive. The portable had an Active Matrix Liguid Crystal
Display with a screen resolution of 640 by 400 pixels.
The computer was 15.25 inches wide by 14.83 inches
deep and the height varied from 2 to 4 inches, front to
back. The weight without a hard disk drive was 13.75
pounds . The keyboard had 63 keys with a unigue
arrangement for locating either a trackball pointing
device or an 18-key numeric keypad on the left or right
hand side of the keyboard. The computer used lead acid
batteries with a power management system controlled by a
6502 microprocessor. This provided 8 to 10 hours of
operation on a single battery charge.
The Atari 400 computer used a MOS 6502
microprocessor operating at 1.8 MHz with 8K bytes of
RAM, expandable to 16K. The display had 16 lines of 32
characters and a high-resolution mode of 320 by 192
PET 2001 The PET 2001 computer used a MOS 6502
microprocessor, had 14K bytes of ROM and 4K bytes of
RAM, expandable to 8K. The 9-inch black and white CRT
could display 25 lines of 40 characters and the 73-key
keyboard included a numeric keypad.
PET 4000 The PET 4000 computer used a MOS 6502
microprocessor, had 18K bytes of ROM and 16K bytes of
RAM, expandable to 32K. The configuration included a 12-
inch green-phosphor display with a capability of showing
25 lines of 40 characters.
Z— 1 The Cromemco Z-l computer used a Zilog Z-80
microprocessor and had 8K bytes of memory.
Z— 2 The Cromemco Z-2 computer used the S-100 Bus with
21 slots for plug- in boards.
Appendix A AA/5
The CTC Datapoint 2200 computer terminal used a
bit-serial processor in TTL logic with shift register
memory. The terminal had a keyboard, 12-line screen
display and two cassette tape drives.
The Digital Computer System was available with
either an AMD 8080A, MOS 6502, Mostek 6800 or Zilog Z-80
microprocessor. The processor board had 2K bytes of RAM.
An input/output board and a video interface board that
provided a 16 line by 32 character display were part of
the system. An optional 8K static RAM board was
available to increase the memory capacity.
The System One computer kit had 82 integrated
circuits, IK bytes of memory, expandable to 8K and used
The HAL-4096, was a home-built 16-bit computer
with 16 registers and 4K bytes of magnetic core memory
from a surplus IBM 1620.
H8 The H8 computer used an Intel 8080 microprocessor,
had IK bytes of ROM and memory cards were available in
4K-byte increments to 32K. It had a unigue 50-pin bus
for expansion cards.
Hll The Hll computer used a DEC LSI-11 microcomputer
board and had a 4K by 16-bit word memory that could
accommodate up to 20K words.
Heath/Zenith-89 The Heath/Zenith-89 computer used a
Zilog Z-80 microprocessor operating at 2.048 MHz and had
16K bytes of RAM, expandable to 48K. The 12-inch screen
could display 24 lines of 80 characters. The keyboard
subsystem and video display used an additional Z-80
Accessories The H9 video terminal had a 67-key keyboard
and the 12-inch CRT could display 12 lines of 80
AA/6 A History of the Personal Computer
The HP 9831A desktop computer used a HP BPC
microprocessor and had 8K bytes of memory, expandable to
32K. The unit had a 32-character LED display, cassette
tape drive and a keyboard.
The Hyperion portable computer had an Intel 8088
microprocessor and 256K bytes of RAM. The storage system
had two 5.25-inch 320K byte double-density dual-sided
floppy-disk drives. The unit had a 7-inch amber-on-gray
monitor that could display 25 lines of 80 characters.
The 28 pound portable unit included an integrated
display, two floppy-disk drives and a detachable
keyboard. The operating system was MS-DOS and the unit
was priced at $4,950 (Canadian) .
5100 The 5100 portable computer had a built-in
keyboard, monitor and magnetic tape cartridge storage
system. The unit used an IBM developed microprocessor
and memory consisted of 48K bytes of ROM and 16K bytes
of RAM, expandable to 64K. The monitor could display 16
lines of 64 characters.
Scamp The Scamp computer used an IBM Palm
microcontroller and had 64K bytes of RAM. The unit had
an integrated keyboard and a small CRT that could
display 16 rows of 64 columns.
System/3 Model 6 This BASIC computer system used
monolithic circuit technology and had 8K bytes of
silicon chip memory, expandable to 16K. The design
included a keyboard for direct data input, a 14-inch
diameter disk storage drive with capacities of 2.5 to
9.8 megabytes and a printer. The CRT could display 15
lines of 64 characters.
Appendix A AA/7
The IMSAI 8080 computer used the Intel 8080A
microprocessor and included 4K bytes of memory. It also
had a heavy duty power supply, commercial-grade paddle
switches on the front panel and a six-slot S-100 Bus
motherboard, expandable to 22 slots.
The Kenbak-1 computer incorporated small and
medium-scale integrated circuits with a memory capacity
of 256 bytes. It had three programming registers, five
addressing modes and very limited input/output
The Mark-8 computer used an Intel 8008
microprocessor, had 256 bytes of memory, expandable to
16K bytes by adding memory boards. The unit had
provision for six circuit board modules.
The Altair 8800 computer used an Intel 8080
microprocessor and had 256 bytes of memory. The Altair
cabinet had space for eighteen cards . The basic unit had
two slots, one for the CPU card and one for the 25 6 byte
The KIM-1 computer used a MOS 6502 microprocessor,
had 2K bytes of ROM that contained the system executive,
and IK bytes of PAM. The unit included an audio cassette
interface, a 23-key keypad and a six-digit LED display.
The Horizon-1 computer used a Zilog Z-80
microprocessor and had 16K bytes of RAM. It also
included one or two 5.25-inch floppy disk drives and a
12-slot S-100 Bus motherboard.
AA/8 A History of the Personal Computer
The Noval 7 60 computer used an Intel 8 08 0A
microprocessor, had 3K bytes of ROM and 16K bytes of
The NRI 832 kit had 52 integrated circuits, 32
bytes of memory, used 15 instructions.
The OSI 400 computer used either a Motorola
MC6800, MOS 6501 or 6502 microprocessor. The unit had
512 bytes of ROM and up to IK bytes of programmable
memory was available. The board was designed for use
with a 48-line expansion bus system.
Poly 88 The Poly-8 8 computer used an Intel
8080 microprocessor, had 512 bytes of RAM and IK bytes
of ROM. It also used the S-100 Bus with four slots, had
a cassette interface
System 8813 The System 8813 computer used an Intel 8080
microprocessor and the video could display 16 lines of
64 characters. The main unit could accommodate from one
to three floppy-disk drives with 90K capacity each.
Sol-10 The Sol-10 Terminal Computer used an
Intel 8080A microprocessor and had IK bytes of PROM, IK
bytes of RAM and IK bytes of video RAM. The computer
could generate a 16-line by 64-character video display.
The unit had a built-in 85-key keyboard and one slot for
a S-100 Bus board.
Sol— 20 The Sol-20 computer used an Intel
8080 microprocessor, had IK bytes of ROM, 8K bytes of
RAM and IK bytes of video RAM. It also had a heavier-
duty power supply and five S-100 Bus expansion slots
Appendix A AA/9
The Micral computer used an Intel 8008
microprocessor and included 256 bytes of RAM, expandable
to one kilobyte. The system used a 60-bit data bus
called Pluribus .
The Scelbi-8H computer used an Intel 8008
microprocessor with up to 4K bytes of memory. The
Scelbi-8B business computer had up to 16K bytes of
Sphere produced three computer models that used
the Motorola MC6800 microprocessor; the Hobbyist,
Intelligent and BASIC. The Hobbyist had 4K bytes of
memory and a keyboard, the Intelligent had more features
and the Basic had 20K bytes of memory and full extended
The SwTPC 68 00 Computer System used a Motorola
MC6800 microprocessor, had 2K bytes of memory,
expandable to 16K. A IK byte ROM chip contained the
mini-operating system. The unit also contained an SS-50
bus for eight interface boards .
TRS-80 The TRS-80 computer used a Zilog Z-80
microprocessor, had 4K bytes of ROM and 4K bytes of RAM,
expandable to 62K. The system included a separate
cassette tape recorder and a 12-inch black and white
monitor that could display 16 lines of 64 characters.
A Disk System Expansion Unit had a disk controller
which could support up to four drives . The diskette had
a capacity of 83K bytes (formatted) with 35 tracks of
2,500 bytes per track divided into ten sectors.
The TI-99/4 computer used a TI TMS9900
microprocessor and had 16K bytes of RAM.
AA/10 A History of the Personal Computer
Alto The Alto computer system had a processor/disk
storage cabinet, graphics display unit, keyboard and a
mouse. The processor unit had a 16-bit custom-made
processor similar to the Data General Nova 1220. The
operating speed was 400,000 instructions per second.
Memory incorporated an address space of 64K 16-bit
words, expandable to 256K. The processor/disk storage
cabinet had two 3-megabyte hard-disk drives. The
graphics unit featured an 8 inch horizontal by 10 inch
vertical black and white display. It used a bit-mapped
raster scan with a resolution of 606 pixels horizontally
by 808 pixels vertically that could display 60 lines of
90 characters. The computer used a detachable keyboard
supplemented by a mouse incorporating three buttons for